NameStart ::= ( Letter | '_' )
where Letter means in one of the Unicode general
categories { Ll, Lu, Lo, Lt, Nl }
We do not allow a name to start with ':'.
see [3] and Appendix B of XML 1.0 specification

Returns true if the encoding name is a valid IANA encoding.
This method does not verify that there is a decoder available
for this encoding, only that the characters are valid for an
IANA encoding name.

NameStart ::= ( Letter | '_' )
where Letter means in one of the Unicode general
categories { Ll, Lu, Lo, Lt, Nl }
We do not allow a name to start with ':'.
see [3] and Appendix B of XML 1.0 specification

Returns true if the encoding name is a valid IANA encoding.
This method does not verify that there is a decoder available
for this encoding, only that the characters are valid for an
IANA encoding name.